This is a Phase I trial of the radiation sensitizer, SR-2508, which is conducted in conjunction with the Radiation Therapy Oncology Group. SR-2508 is a nitroimidazole derivative which was designed to be less lipophilic than its predecessor compounds, misonidazole and desmethylmisonidazole. Preclinical studies indicated that SR-2508 was markedly less toxic to peripheral nerves than prior hypoxic cell radiosensitizers used in clinical trials. The trial has found that up to 3.4 grams per meter squared of SR-2508 can be administered 3 times weekly for 3 weeks in conjuction with standard radiotherapy with less than 50% risk of a limited, grade I peripheral neuropathy. This study has since employed lower daily doses of SR-2508 and it currently appears that 1.7 grams per meter squared may be administered four times per week throughout a six week course of irradiation. Pharmacokinetic data has been generated on the patients entered in this trial, and it appears that the area under the curve calculations of drug exposure are relatively good predictors for the development of peripheral neuropathy.